Conventionally, for example, according to Patent Literature 1, an angle detection mechanism that detects a rotation angle of a throttle valve being a rotation body is provided in an electronic-control throttle-valve device and the like. Then angle detection mechanism includes one throttle position sensor. The throttle position sensor can execute an angle detection of the throttle valve at a control unit, by causing an output voltage transmitted to the control unit to change in response to an angle change of the throttle valve.
In a configuration disclosed in Patent Literature 1, the output voltage of the throttle position sensor is amplified by an amplifier in a low-opening degree region where an opening degree of the throttle valve is small. According to the above, since a resolution of the angle detection in the low-opening degree region can be decreased, the control unit can detect the rotation angle of the throttle valve in the low-opening degree region with a high precision.